Point Out The Error Series 1

Point out the error in the programs. We are discussing the program, its output and explanation.

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1) Program

Our 30-40% of community members thinks error in the program because we are assigning multiple values to one variable. Nothing wrong in this.

We can write

int a;
a = 1,2,3;

Above code is valid code.

In this case, 1 value will assign to a. To know why

Now, check the following program carefully

int main()
{
    int a=1, b, c;
}

In above code, a, b, c three variables are created.

value 1 will assign to a and b,c will get some garbage value.

Below code is similar to above code,

int main()
{
    int a=1, 2, 3;
}

Here 2 and 3 are not valid identifiers . Check this post for naming a variable.

That’s why we got a error

 error: expected identifier or ‘(’ before numeric constant
           int a=1,2,3;
                   ^

Because 2 is not a valid variable name, variable name must start with letter or underscore.

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If you have any doubts, let me know in the comment section .

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2) Program

New C Programming question, point out error in the program #2.

First of all, let me clear the one thing.

#include<stdio.h>
int fun()
{
    return 1;
}
int main()
{
    int a = fun();
    printf("%d",a);
    return 0;
}

The output of above code is 1, because we called function fun(). fun() returns 1 and value 1 is now assigned to variable a .

Now check this code.

#include<stdio.h>
int fun()
{
    return 1;
}
int main()
{
    printf("%d",fun());
    return 0;
}

Here instead of storing the value returning from function fun() into variable a. We directly print it. So the output of above code is also 1.

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Now consider the following code.

#include<stdio.h>

int main()
{
    int a = 1;
    int b = 2;
    int a = 3;    //we can't declare a variable twice in a block
    
    return 0;
}

We can not declare a variable more than once in a block.

#include<stdio.h>
int fun(int a)        // a is declared here
{
    int a = 2;        // we are trying to declare and define variable a twice. And this is invalid
    return a;
}
int main()
{
    printf("%d",fun(1));
    return 0;
}

That’s why the error in the given program is we can not declare variable a twice in a single block i.e. in fun() block.

The error is ( I have used online compiler)

jdoodle.c: In function ‘fun’:
jdoodle.c:4:9: error: ‘a’ redeclared as different kind of symbol
    4 |     int a = 2;        // we are trying to declare and define variable a twice. And this is invalid
      |         ^
jdoodle.c:2:13: note: previous definition of ‘a’ was here
    2 | int fun(int a)        // a is declared here
      |         ~~~~^

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If you have any doubt feel free to mention your doubts in comment section below and if you gain some knowledge then also mention what you gain from this post .

Thank You….

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